In connection with all kinds of garments, and in particular garments used for sports or physical labour, the body exudes perspiration which ideally ought to be transported away from the skin in order to keep it as dry as possible. Since the majority of types of textiles, and especially synthetic textiles, do not have the property that they efficiently transport moisture from the skin, a person, after perspiring, will quite soon begin to feel cold because of the moisture residing in the fabric. This is connected with the fact that the moisture which is removed through evaporation draws much of the heat for the evaporation from the body. One of the few fabrics which seems to have a considerable measure of water transport capacity are woollen fabrics. This is related to the fact that there are capillaries in the wool fibres which have a high liquid transport capacity. When the liquid is drawn away from the skin, evaporation will take place with the aid of heat from the surroundings.
Modern pieces of clothing, and in particular pieces of clothing which are expected to be exposed to perspiration (tracksuits, parka jackets etc.) are often composed of several layers (laminates) of textiles, by means of which an attempt is made to secure insulation together with optimal liquid transport capacity. A known way of optimising this when dressing in cold conditions where perspiration is expected to occur is to have woollen underwear next to the body, which serves to transport the moisture into the outer clothes.
A number of different methods are known which seek to solve this problem in a best possible way. One of these is by using a combination of different types of fibres which have capillary liquid transport properties. German patent publication DE 38 31 970 describes a solution using an electrifiable membrane able to transport liquid according to the principles used in dialysis apparatus.
However, there are no satisfactory solutions which have been put into technical or commercial use, and so the "sweat problem" described above is still perceived as a problem in connection with the aforementioned clothes.